Disable Smilies in This Post. Show Signature: include your profile signature. Only registered users may have signatures.

*If HTML and/or UBB Code are enabled, this means you can use HTML and/or UBB Code in your message.

If you have previously registered, but forgotten your password, click here.

T O P I C R E V I E W

Paul78zephyr

Could Apollo have been placed in a lunar polar orbit? Could a polar (or high latitude) landing have been made from such an orbit with the existing lunar module?

Was it primarily a matter of required fuel? What other factors to consider?

moorouge

One factor has to be that the Kennedy Space Center was not a feasible launch site for a polar orbit mission.

Headshot

NASA categorized an "I" Mission to be a 30-day lunar mapping mission using a manned Apollo spacecraft in polar orbit. The concept was never implemented for reasons with which I am not familiar. Eventually mapping cameras were placed on J Mission CSMs to placate the lunar cartographers.

A Group for Lunar Exploration Planning (GLEP) table issued in Oct 1969 lists such a mapping mission as Alternate 3 for the J-1 Apollo 16's mission assignment. However, this table was apparently a GLEP wish-list published along with a more practical lunar landing site selection list.

This mission was obviously never approved by Apollo management and no details of the discussion (if any) were provided in the source, The International Atlas of Lunar Exploration.

Jim Behling

quote:Originally posted by moorouge:One factor has to be that the Kennedy Space Center was not a feasible launch site for a polar orbit mission.

Not true for lunar polar missions.

Ronpur

Part of the Apollo Applications Program from 1967 included a Lunar Polar Mapping mission of 14 days using a mission module attached to the CSM.

Budget cuts to AAP killed it.

I know I have seen images of a LM modified with a package of instruments in place of the descent stage for this mission, but can not find them now!

Blackarrow

At the time of the Apollo 11 landing, at least one British newspaper (the Daily Mail) published a list of planned landing sites up to and including Apollo 20, together with a one-month mapping mission in lunar polar orbit.

Headshot

Apollo management was very concerned about high-latitude landing sites. Hadley-Apennine, at about 26N, was the most extreme of all Apollo landing sites. Scientists desperately wanted a mission to land at Tycho's North rim, at about 42S, and Apollo management said "no way," but not as politely as that.

The issue was that the further away from the lunar equator a landing site was, the more propellant a lunar module ascent stage would need to effect the plane change necessary to rendezvous with the CSM. The safety margins just were not enough to make flight operations managers comfortable. Roughly forty degrees, north or south, seemed to be where Apollo management drew their line in the sand.

Headshot

quote:Originally posted by Ronpur:I know I have seen images of a LM modified with a package of instruments in place of the descent stage for this mission, but can not find them now!

I recall seeing a similar concept drawing. It was in a 1969 or 1970 issue of Aviation Week & Space Technology.

Ronpur

Okay, I found one from a 1965 Apollo Development video.

Blackarrow

quote:Originally posted by Headshot:...The issue was that the further away from the lunar equator a landing site was, the more propellant a lunar module ascent stage would need to effect the plane change necessary to rendezvous with the CSM...

Not an issue if there was no landing, just a polar-orbiting mission.

Headshot

Correct. But the OP inquired about high latitude landing sites too.

Space Cadet Carl

Great topic! When you read some of the great books and online information about Apollo, you get the strong impression that there were a lot of "how much do we want to roll the dice?" meetings taking place back then. There was considerable risk being argued between administrators, engineers and scientists selecting landing sites. Can you imagine how incredible it would have been to sit in your living room and see color television of Tycho's or Copernicus's central peak from a rover camera on the surface? Unreal.

Captain Apollo

I was 11 when Apollo 11 landed. And sadly I don't expect I will ever see TV from the moon again in my lifetime. Or if I do, then it will be Chinese.

sev8n

quote:Originally posted by Headshot:The issue was that the further away from the lunar equator a landing site was, the more propellant a lunar module ascent stage would need to effect the plane change necessary to rendezvous with the CSM.

This is only an issue if the spacecraft approach path and lunar orbit insertion burn are done to achieve a lunar equatorial orbit.

If the moon was approached above or below the equatorial plane and the LOI burn timed correctly, would the spacecraft not enter a lunar polar orbit? And if so, no propellant need be consumed to achieve plane changes, and latitude would not be a limiting factor in landing site location.

KenDavis

There is a short article in the Summer/Fall 1994 edition of Quest that discusses a possible Lunar Mapping Mission along with a diagram of the CSM and LM modified ascent stage.

Paul78zephyr

Can anyone say how much more fuel, etc, would have been needed to get the CSM/LM stack into (and back out of) lunar polar orbit? Would the LM have needed additional fuel to land/rendezvous with the CSM?

Does the fact that the moon is spinning under the polar orbit complicate the rendezvous?

Jim Behling

The LEO insertion and TLI burn is where the change to lunar polar orbit would be made.

quote:Originally posted by Paul78zephyr:Does the fact that the moon is spinning under the polar orbit complicate the rendezvous?